The field of the disclosure relates generally to gas turbine engines and, more particularly, to domestic bleed circuit seals within a low pressure turbine.
Gas turbine engines include a rotor assembly which is rotatable relative to stationary engine structures, including a rotor mounting structure. The rotor assembly includes a number of rotatable components, such as a central shaft, shaft cones, compressor rotor blades, turbine rotor blades, and dynamic air seals. Each component is reacted upon by static and/or dynamic axial pressure forces. The vector sum of these forces is a net axial force or thrust in either the forward or aft direction. The net thrust places axial loads on the stationary mounting structure, and typically a thrust bearing is employed to absorb the load. At least some known gas turbine engines generate such a large amount of thrust that a thrust balance system is used to balance the net axial load on the thrust bearing.
Furthermore, gas turbine engines typically extract a portion of compressed air from a compressor as bleed air into a domestic bleed circuit that facilitates, among other functions, component cooling, heating, sealing, purging, and thrust control. A portion of bleed air is channeled into turbine cavities for purge. The bleed air is used for preventing combustion gases from being ingested into the cavity and for cooling the turbine rotors. A portion of bleed air is also channeled into the thrust balance system for balancing the net axial load on the thrust bearing. Generally, compressor efficiency is reduced when compressed air is bled from the compressor. When compressor efficiency is reduced, output power of the gas turbine engine is reduced and/or engine fuel consumption is increased, with decreasing overall engine efficiency.